Preparation and properties of zeolite-fly ash-slag composite porous materials: CO2 adsorption performance and mechanical property

Abstract

To solve the environmental problems caused by greenhouse gas emissions, porous materials based on alkaline solid wastes (fly ash and slag) were prepared in this study. Besides, the preparation scheme of the porous materials was optimized through an orthogonal test by taking the compressive strength and static CO₂ adsorption capacity as the target parameters. The two target parameters of the porous materials prepared under the optimal ratio are 15.395 N and 0.83 mmol/g. On the basis of the optimal ratio, zeolite composite porous materials were prepared by adding different types of zeolite, which further improves the CO₂ adsorption capacity of the porous materials. Furthermore, the micro-morphologies, CO₂ adsorption performances, and mechanical properties of the porous materials were analyzed by a scanning electron microscope (SEM), the Brunauer-Emmett-Teller (BET) method, and a universal testing machine. It is discovered that the addition of different types of zeolite decreases the compressive strength but significantly improves the CO₂ adsorption performance as it can promote the specific surface area and the pore volume. Moreover, the best performance is achieved with the addition of 13X zeolite. In this case, the adsorption capacity reaches 2.68 mmol/g, about 3.2 times greater than that of the porous materials without zeolite. The CO₂ adsorbent proposed in this study, which boasts excellent mechanical property and CO₂ adsorption performance, is applicable to goafs and has a bright prospect in the comprehensive utilization of solid wastes and the control of global warming.

Keywords: CO2 adsorption; Compressive strength; Porous materials; Zeolite.